Certain metal oxides, such as titanium dioxide and zinc oxide, are known for their sunscreen properties. Titanium dioxide has low toxicity and is non-irritating to the skin.
Nanostructured particles and materials are currently attracting considerable attention. The small size of nanoparticles (generally used to indicate particles less than 100 nm), which can be responsible for the different properties (electronic, optical, electrical, magnetic, chemical, and mechanical) of nanoparticles and nanostructured materials with respect to the bulk material, makes them suitable for new industrial applications. In many of these new applications, it is imperative to provide and maintain the particles and materials well dispersed in a fluid medium, such as water, organic solvent, wax, oil, polymer or mixtures of these.
Titanium dioxide (TiO2) nanoparticles are substantially transparent to visible light, that is, are transparent, but reflect, scatter and absorb ultraviolet light. The nanoparticles, in contrast to pigment-sized titanium dioxide particles, can be beneficial in sunscreen formulations where transparency of the formulation is desirable.
A major problem with current skin care compositions is that they lack the required durability for long-lasting effects. For this reason, there have been attempts to enhance the binding of the skin care agent to the skin.
A need exists for sunscreen formulations that provide improved durability for long lasting effects.